Impaired sleep is a common problem among older persons, and is associated with reduced daytime function, increased health care costs, increases in falls and injuries, and reduced quality of life. Pilot data from our laboratory at the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute showed that monochromatic 530-nm (green) light delivered through the eyelids before predicted minimum core body temperature (CBTmin) acutely suppressed melatonin and delayed dim light melatonin onset (DLMO). Based on our newly published data on eyelid transmittance, we propose to, in conjunction with investigators at the University of North Carolina at Chapel Hill, test the efficac and acceptance of a device developed to effectively deliver light to phase delay the timing of sleep in older persons with chronic early awakening insomnia, and to assess the effectiveness, acceptance, and safety of this device in the home environment. The light treatment device will have three components: 1) a personal circadian light meter, the Dimesimeter, to collect circadian light/dark and activity/rest patterns; 2) an algorithm to identify the most effective timng to apply circadian light; and 3) a light mask, to deliver 530-nm (green) light during sleep. For Aim 1, we will field test and study the use of this device in 20 older adults with diagnoses of early morning awakenings, and 20 age-matched control subjects. In Aim 2, we will study the use of this device in the home environments of 32 older adults with chronic early awakening insomnia. Because circadian sleep disorders in older adults are one of the primary reasons why caregivers choose to institutionalize their loved ones, a lighting intervention that could improve sleep quality and reduce insomnia in older adults could also potentially delay the transition of older adults to a controlled living environment. Therefore, this project is well-suited for the framework of the PA-11-020 - Technology for Healthy Independent Living Research Grants. Successful introduction of this novel device into clinical settings could lead to the implementation of an economical, non-pharmacological, simple treatment modality that alleviates the adverse consequences associated with early awakening insomnia.